This invention relates to an angular contact ball bearing, and more particularly to an angular contact ball bearing combined with a conical type cage.
An angular contact ball bearing, comprising an inner ring, an outer ring, a plurality of balls disposed between the two rings and a cage holding these balls, is well known. JP-A-2004-52785 Publication discloses a cage called a conical type which can be used as the cage of this angular contact ball bearing. A combination of this conical type cage and the angular contact ball bearing has been extensively used as a preferred form.
Various rolling bearings have been required to have a lightweight design, and with respect to an angular contact ball bearing, it may be proposed to achieve its lightweight design by reducing an axial dimension of an outer ring and/or an inner ring. On the other hand, in a process of assembling angular contact ball bearings, these bearings are often stacked together in an outer ring assembled state or an inner ring-assembled state, and thereafter an outer ring assembly or an inner ring assembly is pulled or taken out from the lower side of the stack.
FIG. 7 shows a condition in which outer ring assemblies 36A, 36B of angular contact ball bearings of a lightweight design are stacked together (Here, only two tiers are shown), each of the outer ring assemblies having balls 34 and a conical type cage 35 incorporated in an outer ring 32. The conical type cage 35 includes a larger-diameter annular portion 38, a smaller-diameter annular portion 39 spaced a predetermined distance from the annular portion 38 in an axial direction, and a plurality of inclined pillar portions 40 arranged at predetermined intervals in the circumferential direction and interconnecting the two annular portions 38 and 39. The cage 35 has a plurality of pockets 41 for respectively receiving the balls 34, each pocket 41 being defined by two adjacent pillar portions 40 and those portions of the two annular portions 38 and 39 extending between these two pillar portions 40.
In the angular contact ball bearings shown in FIG. 7, when the outer ring assembly 36A is to be pulled out from the lower side of the stack of outer ring assemblies 36A and 36B, there is encountered a problem that the lower ring assembly 36A can not be pulled out since the larger-diameter annular portion 38 of the cage 35 of the lower outer ring assembly 36A is fitted in the bore (or inner periphery) of the outer ring 32 of the upper outer ring assembly 36B. Although not shown in the drawings, the same problem is encountered with a stack of inner ring assemblies.
FIG. 8 shows a portion of another related angular contact ball bearing.
In FIG. 8, the angular contact ball bearing 131 comprises an outer ring 132 having a raceway surface 132a formed on its inner periphery, an inner ring 133 having a raceway surface 133a formed on its outer periphery, a plurality of balls 134 disposed between the two rings 132 and 133 and arranged at predetermined intervals in a circumferential direction, and a conical type cage 135 holding these balls 134.
The cage 135 includes a larger-diameter annular portion 138, a smaller-diameter annular portion 139 spaced a predetermined distance from the annular portion 138 in an axial direction, and a plurality of inclined pillar portions 140 arranged at predetermined intervals in the circumferential direction and interconnecting the two annular portions 138 and 139. The cage 135 has a plurality of pockets 141 for respectively receiving the balls 134, each pocket 141 being defined by two adjacent pillar portions 140 and those portions of the two annular portions 138 and 139 extending between these two pillar portions 140.
One end surface (upper end surface) of the outer ring 132 is disposed axially inwardly of (below) an end surface of the larger-diameter annular portion 138 of the cage 135, and one end surface (lower end surface) of the inner ring 133 is disposed axially inwardly of an end surface of the smaller-diameter annular portion 139 of the cage 135. With this construction, a lightweight design of the angular contact ball bearing 131 is achieved.
The angular contact ball bearings 131 are often stacked in a multi-tier manner in an outer ring assembled state in which the balls 134 and the cage 135 are incorporated in the outer ring 132, and the thus stacked angular contact ball bearings 131 are stored and conveyed. Also, the angular contact ball bearings 131 are often stacked together in an inner ring assembled state in which the balls 134 and the cage 135 are incorporated in the inner ring 133, and the thus stacked angular contact ball bearings 131 are stored and conveyed.
FIG. 9 shows a condition in which outer ring assemblies 136A, 136B of the angular contact ball bearings 131 of FIG. 8 are stacked together (Here, only two tiers are shown). In the lowermost outer ring assembly 136A, the lower end surface of the outer ring 132 is held in contact with a placing surface such as a conveyance bed, and a gap is formed between the end surface (lower end surface) of the smaller-diameter annular portion 139 of the cage 135 and the placing surface. In the upper outer ring assembly 136B, the lower end surface of the outer ring 132 is held in contact with the end surface (upper end surface) of the larger-diameter annular portion 138 of the cage 135 of the lower outer ring assembly 136A, and the cages 135 of the adjacent outer ring assemblies 136A and 136B are not contacted with each other.
When the outer ring assemblies 136A and 136B are stacked as shown in FIG. 9, the upper outer ring assembly 136B is placed on the cage 135 of the lower outer ring assembly 136A, and a large load acts between the balls 134 and the raceway surface 132a of the outer ring 132 of the lower outer ring assembly 136A. As a result, when an impact load is applied during conveyance, there is a possibility that brinelling (indentation) and damage occur on the raceway surface 132a of the outer ring 132.